
package com.bpzj.util.messageloop;


import lombok.extern.slf4j.Slf4j;

import java.lang.reflect.Modifier;

/**
 * A Handler allows you to send and process {@link Message} and Runnable objects associated with a thread's {@link MessageQueue}.  Each Handler instance is
 * associated with a single thread and that thread's message queue.  When you create a new Handler, it is bound to the thread / message queue of the thread that
 * is creating it -- from that point on, it will deliver messages and runnables to that message queue and execute them as they come out of the message queue.
 *
 * <p>There are two main uses for a Handler: (1) to schedule messages and
 * runnables to be executed as some point in the future; and (2) to enqueue an action to be performed on a different thread than your own.
 *
 * <p>Scheduling messages is accomplished with the
 * {@link #post}, {@link #postAtTime(Runnable, long)}, {@link #postDelayed}, {@link #sendEmptyMessage}, {@link #sendMessage}, {@link #sendMessageAtTime}, and
 * {@link #sendMessageDelayed} methods.  The <em>post</em> versions allow you to enqueue Runnable objects to be called by the message queue when they are
 * received; the <em>sendMessage</em> versions allow you to enqueue a {@link Message} object containing a bundle of data that will be processed by the Handler's
 * {@link #handleMessage} method (requiring that you implement a subclass of Handler).
 *
 * <p>When posting or sending to a Handler, you can either
 * allow the item to be processed as soon as the message queue is ready to do so, or specify a delay before it gets processed or absolute time for it to be
 * processed.  The latter two allow you to implement timeouts, ticks, and other timing-based behavior.
 *
 * <p>When a
 * process is created for your application, its main thread is dedicated to running a message queue that takes care of managing the top-level application
 * objects (activities, broadcast receivers, etc) and any windows they create.  You can create your own threads, and communicate back with the main application
 * thread through a Handler.  This is done by calling the same <em>post</em> or <em>sendMessage</em> methods as before, but from your new thread.  The given
 * Runnable or Message will then be scheduled in the Handler's message queue and processed when appropriate.
 */
@Slf4j
public class Handler {

  /*
   * Set this flag to true to detect anonymous, local or member classes
   * that extend this Handler class and that are not static. These kind
   * of classes can potentially create leaks.
   */
  private static final boolean FIND_POTENTIAL_LEAKS = false;
  private static final String TAG = "Handler";

  /**
   * Callback interface you can use when instantiating a Handler to avoid having to implement your own subclass of Handler.
   */
  public interface Callback {

    public boolean handleMessage(Message msg);
  }

  /**
   * Subclasses must implement this to receive messages.
   */
  public void handleMessage(Message msg) {
  }

  /**
   * Handle system messages here.
   */
  public void dispatchMessage(Message msg) {
    if (msg.callback != null) {
      handleCallback(msg);
    } else {
      if (mCallback != null) {
        if (mCallback.handleMessage(msg)) {
          return;
        }
      }
      handleMessage(msg);
    }
  }

  /**
   * Default constructor associates this handler with the {@link Looper} for the current thread.
   * <p>
   * If this thread does not have a looper, this handler won't be able to receive messages so an exception is thrown.
   */
  public Handler() {
    this(null, false);
  }

  /**
   * Constructor associates this handler with the {@link Looper} for the current thread and takes a callback interface in which you can handle messages.
   * <p>
   * If this thread does not have a looper, this handler won't be able to receive messages so an exception is thrown.
   *
   * @param callback The callback interface in which to handle messages, or null.
   */
  public Handler(Callback callback) {
    this(callback, false);
  }

  /**
   * Use the provided {@link Looper} instead of the default one.
   *
   * @param looper The looper, must not be null.
   */
  public Handler(Looper looper) {
    this(looper, null, false);
  }

  /**
   * Use the provided {@link Looper} instead of the default one and take a callback interface in which to handle messages.
   *
   * @param looper   The looper, must not be null.
   * @param callback The callback interface in which to handle messages, or null.
   */
  public Handler(Looper looper, Callback callback) {
    this(looper, callback, false);
  }

  /**
   * Use the {@link Looper} for the current thread and set whether the handler should be asynchronous.
   * <p>
   * Handlers are synchronous by default unless this constructor is used to make one that is strictly asynchronous.
   * <p>
   * Asynchronous messages represent interrupts or events that do not require global ordering with represent to synchronous messages.  Asynchronous messages are
   * not subject to the synchronization barriers introduced by {@link MessageQueue#enqueueSyncBarrier(long)}.
   *
   * @param async If true, the handler calls {@link Message#setAsynchronous(boolean)} for each {@link Message} that is sent to it or {@link Runnable} that is
   *              posted to it.
   * @hide
   */
  public Handler(boolean async) {
    this(null, async);
  }

  /**
   * Use the {@link Looper} for the current thread with the specified callback interface and set whether the handler should be asynchronous.
   * <p>
   * Handlers are synchronous by default unless this constructor is used to make one that is strictly asynchronous.
   * <p>
   * Asynchronous messages represent interrupts or events that do not require global ordering with represent to synchronous messages.  Asynchronous messages are
   * not subject to the synchronization barriers introduced by {@link MessageQueue#enqueueSyncBarrier(long)}.
   *
   * @param callback The callback interface in which to handle messages, or null.
   * @param async    If true, the handler calls {@link Message#setAsynchronous(boolean)} for each {@link Message} that is sent to it or {@link Runnable} that is
   *                 posted to it.
   * @hide
   */
  public Handler(Callback callback, boolean async) {
    if (FIND_POTENTIAL_LEAKS) {
      final Class<? extends Handler> klass = getClass();
      if ((klass.isAnonymousClass() || klass.isMemberClass() || klass.isLocalClass()) &&
          (klass.getModifiers() & Modifier.STATIC) == 0) {
        log.info(TAG, "The following Handler class should be static or leaks might occur: " +
            klass.getCanonicalName());
      }
    }

    mLooper = Looper.myLooper();
    if (mLooper == null) {
      throw new RuntimeException(
          "Can't create handler inside thread that has not called Looper.prepare()");
    }
    mQueue = mLooper.mQueue;
    mCallback = callback;
    mAsynchronous = async;
  }

  /**
   * Use the provided {@link Looper} instead of the default one and take a callback interface in which to handle messages.  Also set whether the handler should
   * be asynchronous.
   * <p>
   * Handlers are synchronous by default unless this constructor is used to make one that is strictly asynchronous.
   * <p>
   * Asynchronous messages represent interrupts or events that do not require global ordering with represent to synchronous messages.  Asynchronous messages are
   * not subject to the synchronization barriers introduced by {@link MessageQueue#enqueueSyncBarrier(long)}.
   *
   * @param looper   The looper, must not be null.
   * @param callback The callback interface in which to handle messages, or null.
   * @param async    If true, the handler calls {@link Message#setAsynchronous(boolean)} for each {@link Message} that is sent to it or {@link Runnable} that is
   *                 posted to it.
   * @hide
   */
  public Handler(Looper looper, Callback callback, boolean async) {
    mLooper = looper;
    mQueue = looper.mQueue;
    mCallback = callback;
    mAsynchronous = async;
  }

  /**
   * Returns a string representing the name of the specified message. The default implementation will either return the class name of the message callback if
   * any, or the hexadecimal representation of the message "what" field.
   *
   * @param message The message whose name is being queried
   */
  public String getMessageName(Message message) {
    if (message.callback != null) {
      return message.callback.getClass().getName();
    }
    return "0x" + Integer.toHexString(message.what);
  }

  /**
   * Returns a new {@link Message Message} from the global message pool. More efficient than creating and allocating new instances. The retrieved message has
   * its handler set to this instance (Message.target == this). If you don't want that facility, just call Message.obtain() instead.
   */
  public final Message obtainMessage() {
    return Message.obtain(this);
  }

  /**
   * Same as {@link #obtainMessage()}, except that it also sets the what member of the returned Message.
   *
   * @param what Value to assign to the returned Message.what field.
   * @return A Message from the global message pool.
   */
  public final Message obtainMessage(int what) {
    return Message.obtain(this, what);
  }

  /**
   * Same as {@link #obtainMessage()}, except that it also sets the what and obj members of the returned Message.
   *
   * @param what Value to assign to the returned Message.what field.
   * @param obj  Value to assign to the returned Message.obj field.
   * @return A Message from the global message pool.
   */
  public final Message obtainMessage(int what, Object obj) {
    return Message.obtain(this, what, obj);
  }

  /**
   * Same as {@link #obtainMessage()}, except that it also sets the what, arg1 and arg2 members of the returned Message.
   *
   * @param what Value to assign to the returned Message.what field.
   * @param arg1 Value to assign to the returned Message.arg1 field.
   * @param arg2 Value to assign to the returned Message.arg2 field.
   * @return A Message from the global message pool.
   */
  public final Message obtainMessage(int what, int arg1, int arg2) {
    return Message.obtain(this, what, arg1, arg2);
  }

  /**
   * Same as {@link #obtainMessage()}, except that it also sets the what, obj, arg1,and arg2 values on the returned Message.
   *
   * @param what Value to assign to the returned Message.what field.
   * @param arg1 Value to assign to the returned Message.arg1 field.
   * @param arg2 Value to assign to the returned Message.arg2 field.
   * @param obj  Value to assign to the returned Message.obj field.
   * @return A Message from the global message pool.
   */
  public final Message obtainMessage(int what, int arg1, int arg2, Object obj) {
    return Message.obtain(this, what, arg1, arg2, obj);
  }

  /**
   * Causes the Runnable r to be added to the message queue. The runnable will be run on the thread to which this handler is attached.
   *
   * @param r The Runnable that will be executed.
   * @return Returns true if the Runnable was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   */
  public final boolean post(Runnable r) {
    return sendMessageDelayed(getPostMessage(r), 0);
  }

  /**
   * Causes the Runnable r to be added to the message queue, to be run at a specific time given by <var>uptimeMillis</var>.
   * <b>The time-base is {@link }.</b>
   * The runnable will be run on the thread to which this handler is attached.
   *
   * @param r            The Runnable that will be executed.
   * @param uptimeMillis The absolute time at which the callback should run, using the {@link } time-base.
   * @return Returns true if the Runnable was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.  Note that a result of true does not mean the Runnable will be processed -- if the looper is quit before the delivery time of the
   * message occurs then the message will be dropped.
   */
  public final boolean postAtTime(Runnable r, long uptimeMillis) {
    return sendMessageAtTime(getPostMessage(r), uptimeMillis);
  }

  /**
   * Causes the Runnable r to be added to the message queue, to be run at a specific time given by <var>uptimeMillis</var>.
   * <b>The time-base is {@link }.</b>
   * The runnable will be run on the thread to which this handler is attached.
   *
   * @param r            The Runnable that will be executed.
   * @param uptimeMillis The absolute time at which the callback should run, using the {@link } time-base.
   * @return Returns true if the Runnable was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.  Note that a result of true does not mean the Runnable will be processed -- if the looper is quit before the delivery time of the
   * message occurs then the message will be dropped.
   * @see
   */
  public final boolean postAtTime(Runnable r, Object token, long uptimeMillis) {
    return sendMessageAtTime(getPostMessage(r, token), uptimeMillis);
  }

  /**
   * Causes the Runnable r to be added to the message queue, to be run after the specified amount of time elapses. The runnable will be run on the thread to
   * which this handler is attached.
   *
   * @param r           The Runnable that will be executed.
   * @param delayMillis The delay (in milliseconds) until the Runnable will be executed.
   * @return Returns true if the Runnable was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.  Note that a result of true does not mean the Runnable will be processed -- if the looper is quit before the delivery time of the
   * message occurs then the message will be dropped.
   */
  public final boolean postDelayed(Runnable r, long delayMillis) {
    return sendMessageDelayed(getPostMessage(r), delayMillis);
  }

  /**
   * Posts a message to an object that implements Runnable. Causes the Runnable r to executed on the next iteration through the message queue. The runnable will
   * be run on the thread to which this handler is attached.
   * <b>This method is only for use in very special circumstances -- it
   * can easily starve the message queue, cause ordering problems, or have other unexpected side-effects.</b>
   *
   * @param r The Runnable that will be executed.
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   */
  public final boolean postAtFrontOfQueue(Runnable r) {
    return sendMessageAtFrontOfQueue(getPostMessage(r));
  }

  /**
   * Runs the specified task synchronously.
   * <p>
   * If the current thread is the same as the handler thread, then the runnable runs immediately without being enqueued.  Otherwise, posts the runnable to the
   * handler and waits for it to complete before returning.
   * <p>
   * This method is dangerous!  Improper use can result in deadlocks. Never call this method while any locks are held or use it in a possibly re-entrant
   * manner.
   * <p>
   * This method is occasionally useful in situations where a background thread must synchronously await completion of a task that must run on the handler's
   * thread.  However, this problem is often a symptom of bad design. Consider improving the design (if possible) before resorting to this method.
   * <p>
   * One example of where you might want to use this method is when you just set up a Handler thread and need to perform some initialization steps on it before
   * continuing execution.
   * <p>
   * If timeout occurs then this method returns <code>false</code> but the runnable will remain posted on the handler and may already be in progress or complete
   * at a later time.
   *
   * @param r       The Runnable that will be executed synchronously.
   * @param timeout The timeout in milliseconds, or 0 to wait indefinitely.
   * @return Returns true if the Runnable was successfully executed. Returns false on failure, usually because the looper processing the message queue is
   * exiting.
   * @hide This method is prone to abuse and should probably not be in the API. If we ever do make it part of the API, we might want to rename it to something
   * less funny like runUnsafe().
   */
  public final boolean runWithScissors(final Runnable r, long timeout) {
    if (r == null) {
      throw new IllegalArgumentException("runnable must not be null");
    }
    if (timeout < 0) {
      throw new IllegalArgumentException("timeout must be non-negative");
    }

    if (Looper.myLooper() == mLooper) {
      r.run();
      return true;
    }

    BlockingRunnable br = new BlockingRunnable(r);
    return br.postAndWait(this, timeout);
  }

  /**
   * Remove any pending posts of Runnable r that are in the message queue.
   */
  public final void removeCallbacks(Runnable r) {
    mQueue.removeMessages(this, r, null);
  }

  /**
   * Remove any pending posts of Runnable <var>r</var> with Object
   * <var>token</var> that are in the message queue.  If <var>token</var> is null,
   * all callbacks will be removed.
   */
  public final void removeCallbacks(Runnable r, Object token) {
    mQueue.removeMessages(this, r, token);
  }

  /**
   * Pushes a message onto the end of the message queue after all pending messages before the current time. It will be received in {@link #handleMessage}, in
   * the thread attached to this handler.
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   */
  public final boolean sendMessage(Message msg) {
    return sendMessageDelayed(msg, 0);
  }

  /**
   * Sends a Message containing only the what value.
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   */
  public final boolean sendEmptyMessage(int what) {
    return sendEmptyMessageDelayed(what, 0);
  }

  /**
   * Sends a Message containing only the what value, to be delivered after the specified amount of time elapses.
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   * @see #sendMessageDelayed(Message, long)
   */
  public final boolean sendEmptyMessageDelayed(int what, long delayMillis) {
    Message msg = Message.obtain();
    msg.what = what;
    return sendMessageDelayed(msg, delayMillis);
  }

  /**
   * Sends a Message containing only the what value, to be delivered at a specific time.
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   * @see #sendMessageAtTime(Message, long)
   */

  public final boolean sendEmptyMessageAtTime(int what, long uptimeMillis) {
    Message msg = Message.obtain();
    msg.what = what;
    return sendMessageAtTime(msg, uptimeMillis);
  }

  /**
   * Enqueue a message into the message queue after all pending messages before (current time + delayMillis). You will receive it in {@link #handleMessage}, in
   * the thread attached to this handler.
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.  Note that a result of true does not mean the message will be processed -- if the looper is quit before the delivery time of the
   * message occurs then the message will be dropped.
   */
  public final boolean sendMessageDelayed(Message msg, long delayMillis) {
    if (delayMillis < 0) {
      delayMillis = 0;
    }
    return sendMessageAtTime(msg, System.currentTimeMillis() + delayMillis);
  }

  /**
   * Enqueue a message into the message queue after all pending messages before the absolute time (in milliseconds) <var>uptimeMillis</var>.
   * <b>The time-base is {@link }.</b>
   * You will receive it in {@link #handleMessage}, in the thread attached to this handler.
   *
   * @param uptimeMillis The absolute time at which the message should be delivered, using the {@link } time-base.
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.  Note that a result of true does not mean the message will be processed -- if the looper is quit before the delivery time of the
   * message occurs then the message will be dropped.
   */
  public boolean sendMessageAtTime(Message msg, long uptimeMillis) {
    MessageQueue queue = mQueue;
    if (queue == null) {
      RuntimeException e = new RuntimeException(
          this + " sendMessageAtTime() called with no mQueue");
      log.info("Looper", e.getMessage(), e);
      return false;
    }
    return enqueueMessage(queue, msg, uptimeMillis);
  }

  /**
   * Enqueue a message at the front of the message queue, to be processed on the next iteration of the message loop.  You will receive it in {@link
   * #handleMessage}, in the thread attached to this handler.
   * <b>This method is only for use in very special circumstances -- it
   * can easily starve the message queue, cause ordering problems, or have other unexpected side-effects.</b>
   *
   * @return Returns true if the message was successfully placed in to the message queue.  Returns false on failure, usually because the looper processing the
   * message queue is exiting.
   */
  public final boolean sendMessageAtFrontOfQueue(Message msg) {
    MessageQueue queue = mQueue;
    if (queue == null) {
      RuntimeException e = new RuntimeException(
          this + " sendMessageAtTime() called with no mQueue");
      log.info("Looper", e.getMessage(), e);
      return false;
    }
    return enqueueMessage(queue, msg, 0);
  }

  private boolean enqueueMessage(MessageQueue queue, Message msg, long uptimeMillis) {
    msg.target = this;
    if (mAsynchronous) {
      msg.setAsynchronous(true);
    }
    return queue.enqueueMessage(msg, uptimeMillis);
  }

  /**
   * Remove any pending posts of messages with code 'what' that are in the message queue.
   */
  public final void removeMessages(int what) {
    mQueue.removeMessages(this, what, null);
  }

  /**
   * Remove any pending posts of messages with code 'what' and whose obj is 'object' that are in the message queue.  If <var>object</var> is null, all messages
   * will be removed.
   */
  public final void removeMessages(int what, Object object) {
    mQueue.removeMessages(this, what, object);
  }

  /**
   * Remove any pending posts of callbacks and sent messages whose
   * <var>obj</var> is <var>token</var>.  If <var>token</var> is null,
   * all callbacks and messages will be removed.
   */
  public final void removeCallbacksAndMessages(Object token) {
    mQueue.removeCallbacksAndMessages(this, token);
  }

  /**
   * Check if there are any pending posts of messages with code 'what' in the message queue.
   */
  public final boolean hasMessages(int what) {
    return mQueue.hasMessages(this, what, null);
  }

  /**
   * Check if there are any pending posts of messages with code 'what' and whose obj is 'object' in the message queue.
   */
  public final boolean hasMessages(int what, Object object) {
    return mQueue.hasMessages(this, what, object);
  }

  /**
   * Check if there are any pending posts of messages with callback r in the message queue.
   *
   * @hide
   */
  public final boolean hasCallbacks(Runnable r) {
    return mQueue.hasMessages(this, r, null);
  }

  // if we can get rid of this method, the handler need not remember its loop
  // we could instead export a getMessageQueue() method...
  public final Looper getLooper() {
    return mLooper;
  }

  public final void dump(String prefix) {
    log.info(prefix + this + " @ " + System.currentTimeMillis());
    if (mLooper == null) {
      log.info(prefix + "looper uninitialized");
    } else {
      mLooper.dump(prefix + "  ");
    }
  }

  @Override
  public String toString() {
    return "Handler (" + getClass().getName() + ") {"
        + Integer.toHexString(System.identityHashCode(this))
        + "}";
  }

  // final IMessenger getIMessenger() {
  //     synchronized (mQueue) {
  //         if (mMessenger != null) {
  //             return mMessenger;
  //         }
  //         mMessenger = new MessengerImpl();
  //         return mMessenger;
  //     }
  // }
  //
  // private final class MessengerImpl extends IMessenger.Stub {
  //     public void send(Message msg) {
  //         Handler.this.sendMessage(msg);
  //     }
  // }

  private static Message getPostMessage(Runnable r) {
    Message m = Message.obtain();
    m.callback = r;
    return m;
  }

  private static Message getPostMessage(Runnable r, Object token) {
    Message m = Message.obtain();
    m.obj = token;
    m.callback = r;
    return m;
  }

  private static void handleCallback(Message message) {
    message.callback.run();
  }

  final MessageQueue mQueue;
  final Looper mLooper;
  final Callback mCallback;
  final boolean mAsynchronous;
  // IMessenger mMessenger;

  private static final class BlockingRunnable implements Runnable {

    private final Runnable mTask;
    private boolean mDone;

    public BlockingRunnable(Runnable task) {
      mTask = task;
    }

    @Override
    public void run() {
      try {
        mTask.run();
      } finally {
        synchronized (this) {
          mDone = true;
          notifyAll();
        }
      }
    }

    public boolean postAndWait(Handler handler, long timeout) {
      if (!handler.post(this)) {
        return false;
      }

      synchronized (this) {
        if (timeout > 0) {
          final long expirationTime = System.currentTimeMillis() + timeout;
          while (!mDone) {
            long delay = expirationTime - System.currentTimeMillis();
            if (delay <= 0) {
              return false; // timeout
            }
            try {
              wait(delay);
            } catch (InterruptedException ex) {
            }
          }
        } else {
          while (!mDone) {
            try {
              wait();
            } catch (InterruptedException ex) {
            }
          }
        }
      }
      return true;
    }
  }
}
